Cityscape focus
Oct 17, 2017 10:39:31 #
GLKTN
Loc: TN
via the lens wrote:
Well, since I have not read the Peterson book you ... (show quote)
I use BBF. Here is a Peterson predawn video. https://www.youtube.com/watch?v=NiakXRde4-Q
Oct 18, 2017 06:40:52 #
GLKTN wrote:
I took skyline photos of Nashville around noon. ISO200 f16 @1/250 - 1/350. Nikon d750 at 28 mm. Sunny wb. I auto focused on a building and also tried manual focus. Lesn was nikon 24-120 mm. When I zoom in in post the buldings are not real sharp. Is heat causing a problem? Not sure where to focus. It was a long shot from Love Circle for anyone who may know the location. Pretty long shots.
Long shots lose sharpness because of atmospheric interference, especially heat. You can imagine what astronomers have to go through to get shots of galaxies that are light years away.
Oct 18, 2017 07:43:07 #
If you are really interested in tack sharp landscapes and making large prints, learn how to shoot panos in tiles and merge them in Photoshop. Using telephoto lenses one can capture someone drinking coffee in a building window and print it.
Oct 18, 2017 08:32:49 #
GLKTN
Loc: TN
Thanks everyone. Lots of information I can use. So much to learn. UHH and YouTube are two valuable resources.
Oct 18, 2017 08:53:06 #
anotherview wrote:
Did you set the hyperfocal distance?
As a rule of thumb, you can set the hyperfocal distance by focusing on a point about one-third of the way into the scene.
If properly done, using the hyperfocal distance renders everything in the frame sharp from very near to infinity.
As a rule of thumb, you can set the hyperfocal distance by focusing on a point about one-third of the way into the scene.
If properly done, using the hyperfocal distance renders everything in the frame sharp from very near to infinity.
The use of hyperfocal distance is often misunderstood. See the Cambridge in Colour article, HYPERFOCAL DISTANCE. Under PRECAUTIONS you will see that:
The problem with the hyperfocal distance is that a distant background is on the furthest edge of the depth of field, and is thus barely "acceptably sharp." This may therefore lead to an undesirable loss of detail with images comprised primarily of distant objects (such as many landscapes).
You are bound to be disappointed if you rely on hyperfocal distance, especially if you crop or enlarge your image.
Oct 18, 2017 09:03:19 #
GLKTN
Loc: TN
selmslie wrote:
The use of hyperfocal distance is often misunderst... (show quote)
The only thing I could focus on were the trees about 50 yards, or less, in front of me.
Oct 18, 2017 09:05:21 #
GLKTN
Loc: TN
GLKTN wrote:
The only thing I could focus on were the trees about 50 yards, or less, in front of me.
Maybe more. I don't remember now.
Oct 18, 2017 09:07:12 #
TheDman
Loc: USA
GLKTN wrote:
The only thing I could focus on were the trees about 50 yards, or less, in front of me.
Well there's the problem. If you want tack sharpness on the city buildings you need to focus on them. If autofocus fails you, then you need to focus manually (in live view, zoomed in as far as possible) on a tripod.
Oct 18, 2017 09:10:57 #
GLKTN
Loc: TN
TheDman wrote:
Well there's the problem. If you want tack sharpness on the city buildings you need to focus on them. If autofocus fails you, then you need to focus manually (in live view, zoomed in as far as possible) on a tripod.
I did focus, in auto, on the far buildings. My response was to the hyperfocus response. I tried manual focus but felt I could not improve on auto focus.
Oct 18, 2017 09:16:04 #
TheDman
Loc: USA
GLKTN wrote:
I did focus, in auto, on the far buildings. My response was to the hyperfocus response. I tried manual focus but felt I could not improve on auto focus.
In this case I wouldn't bother with hyperfocal distance. You're trying to get the buildings sharp. The trees in front don't add anything to the scene, so it's not important that they be in focus.
When you focused manually, did you do it zoomed in at 10x?
Oct 18, 2017 09:17:29 #
GLKTN wrote:
The only thing I could focus on were the trees about 50 yards, or less, in front of me.
For full frame at f/13 and 28 mm, focus and depth of field should not be a problem ... until you zoom in during post processing.
There are three possible issues:
1. Zooming in during post processing changes how closely you are looking at the image by changing the crop factor and thereby the effective focal length.
2. Zoom lenses, especially those with a high ratio of min to max focal length, are notoriously poor performers over most of their range. A prime 28 mm lens would do better.
3. Atmospheric distortion (heat waves) will kill sharpness the further the subject is from the camera.
Oct 18, 2017 09:27:38 #
GLKTN
Loc: TN
selmslie wrote:
For full frame at f/13 and 28 mm, focus and depth ... (show quote)
Thanks. Is the Nikon 24-120 f4 a high ratio lens. Not as good as a f2.8 for sure.
Oct 18, 2017 09:33:16 #
Yes, heat could be causing a problem. Understand that depth of field at any aperture is 1/3 in front of the area where the camera acquired focus and 2/3 behind it so focusing 1/3 into the subject at f16 should give you plenty of depth of field to make the buildings sharp.
Oct 18, 2017 09:54:32 #
GLKTN wrote:
Thanks. Is the Nikon 24-120 f4 a high ratio lens. Not as good as a f2.8 for sure.
I would consider anything over 3:1 to be high and anything smaller than f/2.8 makes it difficult for you or your camera to focus.
You might want to look into some of the newer affordable f/1.8 prime lenses. The f/2.8 versions cost about half as much and are almost as good.
Oct 18, 2017 10:01:32 #
CO wrote:
Lenses are usually their sharpest when stopped down 2 to 3 stops from maximum. LensTip.com does extensive lens testing. They tested the Nikon 24-120mm f/4 lens. Here is the chart from their image resolution testing at lens center. You can see at f/16 the resolution is down to about 32 line pairs per millimeter. That lens is its best at f/5.6 where it reaches about 44 line pairs per millimeter.
As was mentioned already, the distance can be a factor also.
As was mentioned already, the distance can be a factor also.
👍 While shooting at f16 will certainly increase your depth of field, the diffraction at small apertures will negatively affect the sharpness. I would have shot this at f5.6 - f8 (certainly no higher than f11) and focused on the buildings, ignoring the trees.
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